2-(2-Imidazolin-2-yl)pyridines and quinolines and their use as herbicidal agents are described in U.S. Pat. Nos. 4,638,068 issued Jan. 20, 1987 and 4,798,619 issued Jan. 17, 1989. These patents describe processes for the preparation of compounds having the structure: ##STR1## wherein A, B, R.sub.1, R.sub.2, W, X, Y and Z represent a wide variety of substituents and demonstrate pre-emergence and post-emergence herbicidal activity for more than three hundred of such imidazolinone pyridines and quinolines. The patents specifically disclose the compound 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-5-methylnicotinic acid and demonstrate the herbicidal activity thereof against a variety of weed species. U.S. Pat. Nos. 4,638,068 and 4,798,619 do not disclose or suggest that 2-(2-imidazolin-2-yl)pyridines and quinolines are active against leguminous weed species (e.g. Cassia obtusifolia L. or Cassia nictitans, L.) either alone or in the presence of a leguminous crop.